Added 7 May 2015: And here it is! Jan Lauridsen in Vardø has photographed this Esperantist card, sent from EKATERINODAR in the Kuban (and only recently under Bolshevik control), routed via Moscow where a Three Triangle censorship mark was applied, addressed to Christiania (= Oslo) and sent via the Northern route with a clear VARDØ transit. Jan L. is trying to get a photo of the front to see if it franked; the correct Tariff was 2 roubles but it may have been sent using the obsolete Free Post tariff. If you look at a map, you can see how indirect is the route followed:
Added 17 April 2015:
.... and Jan Lauridsen in Vardø has sent me scans of a very, very interesting Tarasoff card. You will see that it is registered from Solombala in December 1920 and addressed to Switzerland. The Kerensky card is used as a Blank and the Imperial Arms stamps are revalued x 100 to give a correct - and very rare - 7 rouble franking for a Registered postcard going abroad (Tariff of 30 September 1920). Most importantly, the reverse shows an ARCHANGELSK transit cancel - and also a MURMANSK cancel. This last proves that the card went out by sea (in the middle of the Arctic winter), northwards and westwards towards Norway. At Murmansk the card would have been transferred to a ship headed for Vardø. By 1921 or 1922, as foreign mail handling was centralised, the card would have travelled south - overland - to Moscow or Petrograd and been censored there before being sent on to Switzerland, probably via Germany. But here we have the Northern route still being used, just as it was for the British Occupation card shown above.
I am very grateful to Jan Lauridsen, who is a specialist collector of this Northern route, for letting me show his card here.
Added 19 April 2015: Alexander Epstein sends me scans of two more cards. The first one ,like Lauridsen's, is franked at 7 roubles with the Kerensky card used as a blank. The second card is a non-Tarasoff item, family correspondence written in Swedish and addressed to Finland. Postage Due has been raised, the Kerensky card presumably treated as a blank. Notably, the Archangel transit is clearly a Three Triangle censor mark and this may also be true of the (part) Archangel cancel on the Lauridsen card: